Metering devices

ABSTRACT

In a rotary metering valve, a metering block is located in a chamber having a plurality of outlets. The metering block is connectable to a fluid supply and has an outlet selector rotatable to select one of several different outlets from the block to the chamber. A barrier extends between the wall of the chamber and the metering block to prevent fluid flowing in a 360 degree rotary motion around the block. A sprayer check valve is also disclosed. The valve has a diaphragm acted on by control fluid whose pressure is set to just below the spray fluid pressure and which is varied according to variations in the spray fluid pressure.

FIELD OF THE INVENTION

This invention relates to improvements in metering devices, andparticularly to metering devices used in agricultural and horticulturalspraying devices and related application equipment.

BACKGROUND TO THE INVENTION

Sprayers are used in agriculture and horticulture for applying chemicalsand/or liquid fertilisers to growing crops, and for the treatment ofharvested produce.

Generally, sprayers have a series of outlets across the width of thesprayer boom. Each outlet through which liquid is passed is providedwith a check valve, commonly known as an Anti Drip Check Valve, and thecheck valve is generally equipped with a means to attach a nozzle orapplicator on the downstream side of the check valve. Check valves areprovided to prevent liquid flowing from the outlets when the said liquidis below a predetermined pressure. For example, a check valve may be setup so that liquid may not pass through the valve unless the liquid is atthe intended working or application pressure.

Check valves are available in various different forms. The most commontype used in agricultural and horticultural sprayers comprises a sealingdiaphragm maintained against a sealing face by a compressed coil spring,the spring rate, or loading of which is determined by the pressure atwhich the valve is required to open and the surface area of the sealingdiaphragm.

In practice when the supply pressure to the sprayer boom is switchedoff, the pressure in the boom supply line drops and when below the levelat which it exerts sufficient force to maintain the spring loadeddiaphragm check valve in an open position, the valve shuts. The lengthof time taken for the line pressure to drop after shut off can belengthy, and increases as higher spraying pressures are used. Given thecharacteristics of the spring loaded diaphragm check valve they are notgenerally used in high pressure sprayer applications.

In another type of check valve, a ball loaded against an annular sealingface by a coil spring is used. Ball type check valves are generally usedwhere sprayers are operated at higher pressures, because unlike thespring loaded diaphragm check valve their sensitivity is not dependenton, or effected by, pressure acting over a large surface area towithhold the ball from the point of sealing and therefore provideoutlets with a quicker shut off.

Where high spraying pressures are to be used, it is common to provide aspring loaded check valve downstream of a spring loaded diaphragm valveto facilitate quick shut off of the outlet and manufacturers of checkvalves as described commonly accommodate such practice by providingsuitable fittings to their check valve products.

Certain crops, ground conditions, weather conditions or chemicalsrequire different operating pressures to be used necessitating switchingover from a high pressure application to a low pressure application andvice versa. This causes time delays due to the assembly and disassemblyof components. There is also a risk of components being mixed up and theoperator being contaminated with toxic chemical.

Passive check valves, be they diaphragm or ball valves, share a commonproblem. The problem is that a time delay exists between the moment atwhich the liquid supply is turned off at source, and the time at whichthe pressure in the boom drops sufficiently for the check valves tooperate and so prevent the flow of liquid from the outlets. The furtheraway from the centre of the boom a particular nozzle is, the longer isthe time delay. At present, sprayers having booms of 24 meters are oftenused. When operating at 2.5 to 3.0 bar and depending on the spraynozzles fitted downstream of the outlet, an operator may observe a timedelay of ten seconds between shutting off liquid flow, and liquidceasing to flow through the outlets. This causes crop damage due topatches of crop being overdosed which in turn may lead to environmentaldamage, and is of course a waste of valuable resource. For example, asprayer travelling at 12 km/h may travel 33 meters in the intervalbetween the operator shutting off the flow of liquid and the outletsactually being closed off. There is a particular problem found inbrassica crops when turning at headlands. This is because brassica cropsare very sensitive to chemicals and at row ends and headlands some ofthe crop will almost inevitably be double dosed. This has led farmers toleave field headlands unplanted which represents a considerablereduction in effective land usage.

In some countries stringent environmental protection laws have beenintroduced to limit the application of chemicals, such as fungicides,herbicides, pesticides or fertilisers, per unit area in given timeperiods in order to reduce the risk of ground water being contaminatedby the said chemicals. The potential liabilities, in terms of penalties,resulting from double dosing caused by inaccurate shut-off valves istherefore of prime concern to the farmer.

A further problem posed by spring operated check valves is thatoperating performance is governed by the accuracy of the springs fittedwithin them. Coil springs are manufactured in a manner whereby thespring ratings have wide tolerances. Where springs are designed tooperate check valves at 1.0 bar for instance, due to the tolerance inthe spring rating one check valve may not open until a pressure of 1.1bar is reached, whilst the check valve in an adjacent outlet may open ata pressure of 0.8 bar. Clearly, in the precision application ofchemicals and fertilisers this is most undesirable.

In the spraying of liquid fertilisers it is desirable to operate at lowpressures. This is because higher pressures produce fine droplets in theform of a mist which may remain on the leaves of the plants and lead toburning of the crop. In order to produce large droplets, lower pressuresmust be used. Conventional check valves limit the lower range ofoperating pressures since spring operated check valves do not operatereliably below 1 bar. Whilst liquid fertiliser can be applied at 1 barit is desirable to operate at even lower pressures.

It would therefore be desirable to provide a check valve havingcontrollable shut-off which can be opened at low operating pressures andwhich has very fine tolerances on its opening and closing pressures.

Spring loaded diaphragm check valves of the type so far described poseadditional problems to users. At the time the sprayer boom is folded fortransport, and/or during normal transport to or from the site ofspraying, any liquid remaining in the boom supply lines tends to surge,as a result of movement, which causes localised increases in internalpressure sufficient to open the check valve and thereby allow liquid toescape. Such escape can lead to unintended contact with other crops asthe sprayer passes by, double dosing or worse spraying the operator orpassers by who become contaminated with toxic chemical. Such escapewould permit corrosive solutions to come into contact with the sprayer,and this is particularly damaging in the case where the liquid isfertiliser. It would therefore be desirable to provide a check valvewhich may be adjusted to open and close at any desired pressure. It Isalso desirable to provide a check valve having its shut off at apressure closely adjacent to the operating pressure of the sprayer,which pressure may vary with time, and would therefore allow thepressure in the supply to the inlet to remain at a level close to theoperating pressure required when spraying is resumed. Such a featurewould reduce the time taken for full operating pressure to be achievedwhen the operator switches a sprayer back on when re-entering a crop.

As mentioned above, generally, sprayers have a series of outlets acrossthe width of the sprayer boom. Each outlet through which liquids arepassed is generally provided with a check valve which is generallyequipped with a means to attach a nozzle or applicator on the downstreamside of the check valve. The nozzle or applicator distributes the flowof liquid in a manner specific to the desired or most appropriateapplication method for the given chemical or fertiliser and is generallyselected by the operator who takes into account the liquid being appliedas well as crop and weather conditions and intended speed ofapplication. In many cases the nozzle or applicator design is such thatthe outlet design regulates the flow of liquid and at the same timedisperses the liquid in an optimum fashion. For example, a fan jetnozzle will regulate the flow of liquid dependent of the liquid pressureand then distribute the liquid in droplets of a particular size anddensity in a fan shaped pattern.

There are nozzles and applicators which do not embody the samecharacteristics as the type previously describes, and which thereforerequire additional and separate methods of regulating or metering theflow so as to provided a necessary control on the volume of liquidflowing from the particular sprayer outlet. In different applications itmay be necessary to apply different volumes of liquid. In order toprovide for this metering discs or nozzles are used, the metering discsgenerally fitting between the nozzle or applicator attaching means andthe outlet or the outlet of the check valve. When applying liquidfertiliser with a dribble bar, a metering disc is used.

A metering disc generally has an aperture in its centre, the diameter ofthe aperture providing for a range of application volumes over the rangeof pressures for which the nozzle or applicator is designed to operate.When the limits of the range are reached, it is necessary to change themetering valve for another having a differently sized aperture.

There are many different sized metering discs or orifices available,typically however, to cover the requirements of most agricultural andhorticultural applications three different metering discs are needed forany one nozzle or applicator. The time taken to change the metering discfor each outlet is great, and as the size of booms tends to increase sodoes the significance of the time taken to change meteringdiscs/nozzles.

It would therefore be desirable to provide a metering mechanism whichdoes not require the changing of metering discs and which provides arange of metering which spans most commonly used application rates.

SUMMARY OF THE INVENTION

The invention provides a check valve comprising a body having an inletand an outlet, an inlet chamber and an outlet chamber mounted in thesaid body between the inlet and the outlet, the said inlet chamber beingprovided with a check valve to permit or prevent the flow of liquid fromthe inlet chamber to the outlet chamber, the check valve comprising adiaphragm and pressurising means to exert a pressure on the saiddiaphragm, wherein the pressurising means provides for a variablepressure to be exerted on the said diaphragm.

One aspect of the invention provides a kit of parts comprising adiaphragm and pressurising means to exert a pressure on the saiddiaphragm when said diaphragm is attached to a check valve comprising abody having an inlet and an outlet, an inlet chamber and an outletchamber mounted in the said body between the inlet and the outlet, thesaid inlet chamber being provided with a check valve to permit orprevent the flow of liquid from the inlet chamber to the outlet chamber,wherein the pressurising means provides for a variable pressure to beexerted on the said diaphragm.

The pressurising means may be pneumatic, or hydraulic. Alternatively.the pressurising means may comprise an electrically or electronicallyactivated actuator, such as a solenoid.

The pressurising means may exert a pressure in the range 0.3 Bar to 6Bar on the diaphragm.

In another embodiment of the invention, the pressurising means may exerta pressure of up to 20 Bar. Such high pressures are often used in aerialcrop spraying.

Advantageously, the diaphragm is formed from an elastomeric material,and preferably the thickness of the diaphragm is between 0.5 and 1.5 mm.

Preferably, the diaphragm is held in place by an end cap. The end capand the body may be provided with co-operating attachment means. Theattachment means may be a bayonet fitting, or screw threads.

In one embodiment of the invention, the cap comprises an aperture and anozzle to which an air or hydraulic supply may be attached.

Where the pressurising means is hydraulic or pneumatic the diaphragm maybe pre-shaped and/or pre-stressed so that as the pressure exerted by thepressurising means decreases the diaphragm lifts away from its sealingposition. Preferably, the diaphragm is pre-stressed so that in a restingposition it is in compression. Advantageously, the diaphragm is verythin in cross-section.

The combination of a diaphragm which is both thin and pre-shaped and/orpre-stressed results in a diaphragm that is very sensitive and whichresponds very quickly to changes in pressure exerted on the diaphragm bythe pressurising means, thereby enabling fast and accurate shut off oropening of fluid flow from the inlet to the outlet of the check valve.

The outlet chamber may comprise a pipe which extends within the inletchamber.

A dribble bar, or any other suitable nozzle, may be attached to theoutlet, and the body of the valve may be adapted to provide for suchattachment.

In one embodiment of the invention there is provided a detection andcontrol means to detect the fluid pressure in the body of the valve andadjust the pressure exerted by the pressurising means in response to thedetected fluid pressure thereby providing shut off pressures which arein close proximity to actual operating pressures. The fluid pressure maybe detected in the inlet chamber or the supply to the inlet. Thepressure exerted by the pressurising means may follow the fluid sprayingpressure, so that the pressure exerted by the pressurising means on thediaphragm is only fractionally greater or less than the spraying fluidpressure.

The control means may be adapted to cause the pressurising means toexert sufficient pressure to cause shut off of the check valve when thefluid pressure falls below a pre-set value. The control means may bearranged to exert a pressure on the diaphragm which is proportional tothe fluid pressure detected. Alternatively, the control means may bearranged to exert a pressure on the diaphragm which is a greater or lessthan the fluid pressure by a fixed amount, e.g. 0.5 bar greater or lessthan the fluid pressure.

The invention provides a rotary metering valve comprising a meteringblock having an inlet connectable to a fluid supply and at least oneoutlet, and an outlet selector having at least one aperture therein foralignment with an outlet of the metering block to permit flow of a fluidtherethrough, wherein the outlet selector and the metering block arearranged to permit relative rotation of one with respect to the other,and a means to rotate the outlet selector and/or the metering block.

The metering block may be cylindrical. The outlet selector may becylindrical.

Typically the outlet selector is arranged to envelop a portion of themetering block, or to be enveloped by a portion of the metering block.

The metering block may be provided with a plurality of outlets and theoutlet selector is provided with one aperture. The metering block issuitably provided with three outlets. The metering block may be providedwith one outlet and the outlet selector may be provided with a pluralityof outlets. The metering block may be provided with a plurality ofoutlets and the outlet selector may be provided with a plurality ofapertures. The or each outlet of the metering block may comprise a borein a wall thereof. Where more than one outlet is provided in themetering block, the sizes of the outlets may differ. Where more than oneaperture is provided in the outlet selector, the sizes of the aperturesmay differ.

The metering block may be fixed and the outlet selector may rotaterelative to the said metering block. Alternatively, the outlet selectormay be fixed and the metering block may rotate relative to the saidoutlet selector.

The metering block may be secured in a body. Preferably, the outletselector fits over the metering block, and more preferably, a cap holdsthe metering block and the outlet selector in position within the body.The cap may be held in place by screw threads, a bayonet fitting, orother suitable attachment means. The cap may sit against an externalflange.

Preferably, the cap has a portion through which part of the outletselector extends, seals such as “O” rings being provided to preventegress of fluid from within the body through the cap.

The metering block and outlet selector assembly may be mounted in abody, which body may be provided with at least one outlet. The body maycomprise multiple outlets and may be substantially cylindrical. The bodyis suitably a dribble bar having multiple outlets.

In certain circumstances instead of an equal amount of liquid flowingfrom each of the body's outlets a different amount of fluid can flowfrom each outlet. This can be due to a rotational flow occurring betweenthe inner wall of the body and the metering block and outlet selectorassembly.

In one embodiment of the invention a barrier is provided between aninner surface the body and the metering block and outlet selectorassembly. The barrier may extend from an inner wall of the body to themetering block and outlet assembly. The barrier may abut the outletselector or the metering block. The barrier serves to balance and breakflow of a rotational nature and is so formed to enable the accuratedivision of liquid between the outlets in the body.

Advantageously, the barrier is so located and dimensioned as to providefor an accurate division of liquid between the outlets in the body, theflow through each outlet being within the tolerance requirements forconstancy of flow from singularly fed nozzles having multiple outlets asset out in national, international or industry standards and codes.

The barrier may be aligned with an axial centre line of the body,outlets being located to either side of the centre line. An equal numberof outlets may be provided on either side of the said centre line.

In another embodiment of the invention, the number of outlets to eitherside of the centre line may be unequal, and the barrier may bepositioned in the body to ensure that the flow to each outlet is equal.

The position of the barrier with respect to the outlet of the outletselector and metering block assembly into the body can also effect theflow from the outlets in the body. The barrier may be aligned with theoutlet of the outlet selector and metering valve assembly, or thebarrier may be off-set from the outlet of the outlet selector andmetering valve assembly.

The means to rotate the outlet selector may be a hand grip, lever, orspanner flats, and the said means may be provided on the part of theoutlet selector which extends through the cap.

Alternatively, the means to rotate the outlet selector and/or themetering block may comprise an actuator, which actuator may be activatedremotely, for example by a controller.

The body may be part of an outlet fitting for a sprayer or may be partof the nozzle which attaches to a sprayer outlet through which fluidfinally leaves the sprayer.

Preferably the metering block is formed from stainless steel or suitablepolymers or thermoplastics, which may be of the type known asengineering plastics. Alternatively, the metering block may be formedfrom brass, ceramics or other suitable materials.

The outlet selector and/or the body may be formed from a polymer orthermoplastic. Alternatively, the outlet selector and/or the body may beformed from machined or cast ferrous or non ferrous materials.

One aspect of the invention provides a valve assembly comprising a checkvalve comprising a body having an inlet and an outlet, an inlet chamberand an outlet chamber mounted in the said body between the inlet and theoutlet, wherein the inlet chamber there is provided with a diaphragmwhich permits or prevents the flow of liquid from the inlet chamber tothe outlet chamber, and pressurising means to exert a pressure on thesaid diaphragm, and the outlet chamber being provided with a rotarymetering valve comprising a metering block having an inlet connectableto a fluid supply and at least one outlet, and an outlet selector havingat least one aperture therein for alignment with an outlet of themetering block to permit flow of a fluid therethrough, the outletselector and the metering block being arranged to permit relativerotation of one with respect to the other, and a means to rotate theoutlet selector and/or the metering block is provided.

Preferably, the diaphragm is provided at upstream end of the inletchamber.

The pressurising means may be hydraulically, pneumatically, electricallyor mechanically operated. For example, the diaphragm may be held againsta sealing face by means of a spring.

Advantageously, the rotary metering valve is attached to the downstreamend of the outlet chamber.

The pressurising means may permit a variable pressure to be exerted onthe said diaphragm.

According to another aspect of the invention, there is provided asprayer having a check valve and/or a metering valve according to theinvention.

In one embodiment of the invention, the control means may communicatewith a satellite derived or computer generated mapping system, shuttingoff and opening one or more of the valves, and/or adjusting one or morerotary metering valve in accordance with information received from thesaid mapping system. The rotary metering valves may be motorised toenable them to be adjusted in response to a signal from the said mappingsystem.

The invention provides a metering valve which does not requiredisassembly in order to adjust the size of the aperture through whichthe liquid passes.

In one embodiment of the invention check valves according to theinvention are controlled as a group in order to control fluid flow fromindividual sections of a sprayer boom. By using check valves in thismanner, the use of mechanical fluid control valves, to shut off fluidbeing supplied to individual sections of a sprayer boom is not required.The arrangement also permits the sprayer to be equipped with one singlefeed line for the spray boom as opposed to sprayers of the prior artwhich have a plurality of fluid supply lines, the number of supply linescorresponding to the number of sections on the boom.

Another embodiment of the invention provides a sprayer comprising a tankprovided with a feed line which extends from and returns to the tank,wherein the feed line is provided a valve to control the return of fluidin the feed line to the tank. Advantageously, the sprayer is providedwith a controller and the said valve is controlled by the controller.

The sprayer is preferably provided with a pressure regulator whichmaintains the pressure in the feed line constant.

Preferably, the valve is a check valve according to the invention. Thecheck valve may comprise a rotary metering valve according to theinvention.

Alternatively, the valve may be a regulating valve such as a rotaryvalve, or a gate valve.

The provision of this feature allows chemical solutions to circulateconstantly through the feed lines of sprayer boom even when the sprayeris not operating, so that the chemical remains mixed and available tothe outlets at the required spraying pressure at all times. There-circulation of liquid suspensions such as fertilisers is extremelydesirable to ensure that they are applied to crops in a consistentsolution and this feature provides a means of achieving this.

The valve provided in the feed line to control the return of fluid inthe feed line to the tank may be used to allow recirculation duringspraying. Where the valve is a check valve according to the inventionthe outlet of the valve may be of a size which permits a desiredre-circulatory flow rate when the check valves controlling the flow offluid through the sprayer nozzles are open. By combining a rotarymetering valve with the check valve, different re-circulatory flow ratescan be provided for. Alternatively, a regulating valve may be used inthe feed line. In each case the position of the valve may be controlledby the controller.

Another benefit of the valve in the feed line to control the return offluid in the feed line to the tank, is that a further means ofcontrolling the flow rate of fluid through the sprayer nozzles isprovided. This is because a proportion of fluid which would have passedthrough the nozzles is being returned to tank.

The check valve of the invention enables the time delay during the buildup to operating pressure following check valve shut-off and resumptionof spraying to be kept to a minimum. The speed at which the check valveoperates can be adjusted by varying the pressure exerted on thediaphragm by the pressurising means. Increasing the pressure increasesthe speed of operation of the check valve.

Due to the absence of mechanical springs, the check valve of theinvention does not suffer from variance in tolerance of spring ratings,and therefore is much safer and more accurate than presently availablecheck valves, both in terms of crop and environmental damage.Furthermore, when used on a sprayer, where it is necessary to change theoperating pressure thereof, rather than physically changing springs oractual check valves, the degree to which the diaphragm is pressurisedmay simply be adjusted either manually or by a control system asdescribed herein.

The metering devices of the invention may be used in many differentapplications, but are particularly suited for use with agricultural andhorticultural spraying machines. Furthermore, the metering devices ofthe invention can be supplied as integral components within nozzles orapplicators which are fitted to spraying machines or as integral partswithin check valve assemblies which may be retro-fitted to existingsprayers. Retro-fit kits may use existing outlet fittings and in thecase of a check valve replaces the spring with a pressurising means ofthe invention, or in the case of a rotary metering valve replaces themetering disc.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which illustrate exemplary embodiments of theinvention:

FIG. 1 is a schematic layout of a sprayer according to the invention;

FIG. 2 is a cross-section through a sprayer fitting having a pneumaticcheck valve and a metering valve according to the invention;

FIG. 3 is a cross-section through a sprayer fitting having an hydrauliccheck valve and a metering valve according to the invention;

FIG. 4 is a cross-section through a sprayer fitting having apneumatically or hydraulically operated check valve according to theinvention;

FIG. 5 is a cross-section through a sprayer fitting having a check valveof the type found in the prior art and a metering valve according to theinvention;

FIG. 6 is a cross-section through a sprayer fitting having a pneumaticcheck valve, with the check valve in its open position, and a meteringvalve according to the invention;

FIG. 7 is a cross section through a dribble bar, the outlets of thedribble bar being connected to a metering valve according to theinvention;

FIG. 8 is a cross-section through the a dribble bar as shown in FIG. 7,but to a larger scale; and

FIG. 9 is a graph showing a pressure sequence for sprayer operation asmonitored and followed by the control system shown in FIG. 1.

FIG. 10 is schematic layout of a metering device according to theinvention;

FIG. 11a is a cut away schematic elevation of the metering deviceaccording to the invention without a barrier;

FIG. 11b is a cut away schematic elevation of the metering deviceaccording to the invention with a barrier;

FIG. 12 is a cross-section through a dribble bar applicator, the outletsof the dribble bar being connected to a metering valve according to theinvention;

FIG. 13 is a cross-section through a sprayer fitting having apneumatically or hydraulically operated check valve according to theinvention;

FIG. 14 is a cross-section through a sprayer fitting having a checkvalve of the type found in the prior art and a metering valve accordingto the invention;

FIG. 15 is a schematic layout of a sprayer fitted with check valves ofthe invention which uses these valves as the means of boom sectioncontrol.

FIG. 16 is a cross-section of a diaphragm for use in a metering deviceaccording to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 2, there is shown a fitting 1 having a main body 2which is externally threaded 3 to provide for attachment of the fittingto an outlet on a sprayer boom (not shown). Attachment of the fitting toan outlet on a sprayer could be provided by a clamp arrangement or aspigot. The main body 2 is provided with an inlet in the form of a bore4 which enters into the inlet chamber 5 of the body 2. Running centrallythrough the inlet chamber 5 is an internal spigot 6 which is hollow. Anelastomeric diaphragm 7 sits on one end of the body 2 and the internalspigot 6 to prevent the flow of liquid through bore 4, inlet chamber 5and through the hollow internal spigot 6. Diaphragm 7 is held inposition by an end cap 8 which may be attached to the main body 2 bymeans of a bayonet fitting or threads. The cap 8 is provided with anattachment member 9 suitable for attachment to an air supply. Cap 8 hasan aperture 10 therein which permits the passage of air into the chamber11 between the inner face 12 of the cap 8 and the outer face 13 of thediaphragm 7. The effect of supplying air is to pressurize the chamber11. Diaphragm 7 moves away from the end of internal spigot 6 when theliquid pressure in chamber 5 exceeds the force created by the airpressure in chamber 11 which acts on diaphragm 7. By adjusting the airpressure In chamber 11 the valve may be activated at any desiredpressure, subject to the specification of the materials of the diaphragmand the other components of the fitting.

When the pressure of the liquid in chamber 5 exceeds the force createdby the air pressure in chamber 11 which acts on diaphragm 7, liquidflows into the hollow centre of internal spigot 6.

At one end of the internal spigot 6 there is provided a metering valveassembly 14 which comprises a metering block 15 which is locked into themain body 2 by suitable locking means and a rotatably mounted outletselector 16 having a grip portion 17, the valve assembly 14 being heldin place by a cap 18.

The metering block 15 has an internal chamber 23 around thecircumference of which there are located a plurality of apertures 24, 25and 26 of different diameters. The outlet selector 16 is also providedwith an aperture 22. By grasping the grip portion 17, the outletselector can be rotated so that aperture 22 is aligned with a desiredone of the apertures 24, 25 or 26. The diameters of the apertures 24, 25and 26 determine the flow of liquid through aperture 22 into outletchamber 27 which has a portion 28 adapted to receive a spray nozzle ordribble bar for instance.

The interface between the internal spigot 6 and the metering block 23 issealed by an “O” ring 21. The interface between the metering block 23and the outlet member is similarly sealed by an “O” ring 20. Theinterface between the outlet selector 16 and the cap 18 is sealed by an“O” ring 19.

Cap 18 may be attached to the main body 2 by means of a bayonet fittingor by threads.

The outlet selector 16 and cap 18 may be provided with means to indicatewhich of the outlets 24, 25 or 26 is in alignment with the aperture 22.

The fitting shown in FIG. 3 is identical to the fitting shown in FIG. 2but the elastomeric diaphragm 7 is actuated hydraulically rather thanpneumatically.

Referring now to FIG. 4, there is shown a fitting 30 having a main body31 which is externally threaded 32 to provide for attachment of thefitting to a sprayer boom (not shown). Attachment of the fitting to asprayer boom may be provided by a damp arrangement or a spigot insteadof a screw thread. The main body 30 is provided with an inlet in theform of a bore 33 which enters into the inlet chamber 34 of the body 31.Running centrally through the inlet chamber 34 is an internal spigot 35which is hollow to allow liquid to flow therethrough. An elastomericdiaphragm 36 sits on one end of the body 31 and the internal spigot 35to prevent the flow of liquid through bore 33, inlet chamber 34 andthrough the hollow internal spigot 35. Diaphragm 36 is held in positionby an end cap which may be attached to the main body 31 by means of abayonet fitting or threads. The cap 37 is provided with an attachmentmember 38 suitable for attachment to an air or hydraulic fluid supply.Cap 37 has an aperture 39 therein which permits the passage of air orhydraulic fluid into the chamber 40 between the inner face 41 of the cap37 and the outer face 42 of the diaphragm 36. The effect of supplyingair or hydraulic fluid is to pressurize the chamber 40. Diaphragm 36moves away from the end of internal spigot 6 when the liquid pressure inchamber 34 exceeds the force created by the air or hydraulic pressure inchamber 40 which acts on diaphragm 36. By adjusting the air or hydraulicpressure in chamber 40 the check valve may be activated at any desiredpressure, subject to the specification of the materials of the diaphragmand the other components of the fitting.

When the pressure of the liquid in chamber 34 exceed the air pressure inchamber 40, liquid flows into the hollow centre of internal spigot 35.

One end of internal spigot 35 has a portion 43 adapted to receive aspray nozzle or dribble bar for instance.

Referring to FIG. 5, there is shown a fitting 50 having a main body 51which is externally threaded 52 to provide for attachment of the fittingto an outlet on a sprayer boom (not shown). Attachment of the fitting toa sprayer boom may be provided by a clamp arrangement or a spigotinstead of a screw thread. The main body 51 is provided with an inlet inthe form of a bore 53 which enters into the inlet chamber 54 of the body51. Running centrally through the inlet chamber 54 is an internal spigot56 which is hollow. An elastomeric diaphragm 57 sits on one end of thebody 51 and the internal spigot 56 to prevent the flow of liquid throughbore 53, inlet chamber 54 and through the hollow internal spigot 56.Diaphragm 57 is held in position by an end cap 58 which may be attachedto the main body 51 by means of a bayonet fitting 55, 63 oralternatively by threads. The cap 58 has a piston 59 slidably mountedtherein. The stem 60 of piston 59 slides in a bore in cap 58, inwardmovement of the piston being limited by cap 61. Piston 59 is biased byspring 62 to force diaphragm 57 into a position where liquid may notflow through bore 53, chamber 54 and subsequently into internal spigot56. When the pressure in the liquid exceeds the force generated by thespring, the piston 59 moves backwards to permit the flow of fluid frombore 53, through chamber 54 and into the hollow centre of internalspigot 56.

At one end of the internal spigot 56 there is provided a metering valveassembly 64 which comprises a metering block 65 which is suitably lockedinto the main body 51 and a rotatably mounted outlet selector 70 havinga grip portion 75, the valve assembly 64 being held in place by a cap74.

The metering block 65 has an internal chamber 69 around thecircumference of which there is located a plurality of apertures 66, 67and 68 of different diameters. The outlet selector 70 is also providedwith an aperture 78. By grasping the grip portion 75. the outletselector can be rotated so that aperture 78 is aligned with a desiredone of the apertures 66, 67 or 68. The diameters of the apertures 66, 67and 68 determine the flow of liquid through aperture 78 into outletchamber 76 which has a portion 77 adapted to receive a spray nozzle ordribble bar for instance. The interface between the internal spigot 56and the metering block 65 is sealed by an “O” ring 73. The interfacebetween the metering block 65 and the outlet selector is similarlysealed by an “O” ring 72. The interface between the outlet selector 70and the cap 75 is sealed by an “O” ring 71.

Cap 74 may be attached to the main body 51 by means of a bayonet fittingor by threads.

The outlet selector 70 and cap 74 may be provided with means to indicatewhich of the outlets 66, 67 or 68 is in alignment with the aperture 78.

In FIG. 6 the fitting 1 shown in FIG. 2 is illustrated, but with theelastomeric diaphragm 7 in an open position which permits the flow offluid through bore 4, chamber 5 and through the hollow centre ofinternal spigot 6.

FIGS. 7 and 8 illustrate a dribble bar 80 having a metering valve 81according to the invention and a plurality of outlets 82, each outletbeing connected to the metering valve by pipes 83, 84. A groove 86 isprovided in stem 85 to permit fitting of the dribble bar 80 to aconventional sprayer outlet, or to a sprayer outlet provided with acheck valve according to the present invention, such as that shown inFIG. 4.

FIG. 8 shows the metering valve 81 in detail, the metering valvecomprising a metering block 87 and a rotatably mounted outlet selector91 having a grip portion 92, the valve 81 being held in place by a cap97.

The metering block 87 has an internal chamber 98 around thecircumference of which there is located a plurality of apertures 88, 89and 90 of different diameters. The outlet selector 91 is also providedwith an aperture 93. By grasping the grip portion 92, the outletselector can be rotated so that aperture 93 is aligned with a desiredone of the apertures 88, 89 or 90. The diameter of the apertures 88, 89and 90 determine the flow of liquid through aperture 93 into outletchamber 94 which enters into portion 95 for connection to pipes 82, 83by means of adapter 96.

The metering valve 81 is sealed by “O” rings where appropriate.

Cap 97 may be attached to the main body 99 by means of a bayonet fittingor by threads.

The outlet selector 91 and cap 97 may be provided with means to indicatewhich of the outlets 88, 89 or 90 is in alignment with the aperture 93.

Referring now to FIG. 1, there is shown a layout diagram for a sprayer200 according to the invention, the sprayer comprising a tank 201holding a liquid 202 to be sprayed through a fitting 226 according tothe invention as shown in FIGS. 2 and 6.

A pipe 203 enters the base of tank 201, and liquid is drawn out of thetank by pump 205 through filter 204. To the down stream side of the pump205 pipe 203 continues back to the tank 201, a by pass valve beingprovided between the pump 205 and the point at which the pipe 203returns to the tank 201.

A pipe 207 branches from pipe 203 to supply liquid to a plurality ofvalves connected in series. The first valve is a hydraulic relief valve209 which may be set manually or automatically monitored, and isconnected to the second valve which is an on/off valve 210. If thepressure of the liquid in the hydraulic relief valve 209 exceeds apre-set value, liquid is returned to the tank 201 through pipe 208. Thethird valve is a pressure control valve 211 which is connected to asprayer control device 224. The sprayer control device has means tomeasure the pressure in the liquid and means to adjust the saidpressure. Such devices are well known to those skilled In the art, andtherefore the sprayer control device 224 is not described in detail. Thethird, fourth and fifth valves in the series are on/off valves 212. Thepurpose of the three valves 212 is to enable individual sections of thesprayer boom (not shown) to be switched on or off. The number of valves212 corresponds to the number of sections of the boom. Pipes 213 connectto the on/off valves 212 and the sprayer fitting 226 to allow the liquid202 to be sprayed as desired. Sprayer fitting is connected to an airline 216.

A compressor 220 is powered by battery 223, which also powers sprayercontrol device 224,225, and the battery 223 may be the battery of atractor. Compressor 220 is pneumatically connected by air line 222 toreservoir 221, the air line 222 continuing from reservoir 222 to aseries of valves. The first valve is an electrically controlledregulating valve 217 which is electrically connected 215 to aproportional control unit in the control box. The proportional controlunit in the control box 225 detects the pressure in pipe 214 (set by thesprayer control device 224, 225) and sets the air pressure so that it isless than the pressure of the liquid, e.g. the liquid pressure may beset at 0.8 bar whilst the air pressure is set at 0.7 bar. The secondvalve 218 is simply an on/off valve, whilst each of valves 219 is anon/off valve. The number of valves 219 corresponds to the number of boomsections.

In operation, when the sprayer control device is switched to on, the airline 216 is pressurized to a desired degree, such as 0.7 bar. This meansthat if the pressure in the liquid falls below 0.7 bar, the check valvewill not allow liquid to flow through the fitting 226.

The pressure of the liquid and/or the air pressure may be adjusted toany desired pressure within the normal range of pressures used for sprayapplications. The differential between the pressure of the liquid andthe air pressure may be fixed or variable.

The number of on/off valves on the control side of the layout showncorresponds to the number of boom sections on the sprayer. The controlside could be configured with only one on/off valve thereby treating thesprayer boom as if it were only one boom section, or with many on/offvalves up to one on/off valve for each outlet.

In FIG. 1, the pneumatic lines 216 and corresponding proportioner,controls and pressurising means may be replaced by electricaltransducers, controls and solenoid valves at the outlets.

Referring now to FIG. 9, there is shown a pressure sequence for sprayeroperation as monitored and followed by the control system shown in FIG.1. From the start of sprayer operation to time A, the hydraulic pressure(shown by the broken line) rises from zero to the operating pressure of2.8 bar. The air pressure (shown by a solid line) rises from 0.5 bar to2.3 bar. At the start, the air pressure is greater than the hydraulicpressure, thereby ensuring shut off of the outlets. The control systemis set up so that the air pressure remains approximately 20 percent lessthan the hydraulic pressure and it can be seen that when the operatorreduces the hydraulic pressure, so the air pressure falls.

At A the operator switches off either a valve 112 or the main on/offvalve 110. This causes a rapid drop in hydraulic pressure. Upondetecting this rapid drop in pressure, the control system causes thepneumatic pressure to rise above the last maximum detected hydraulicpressure. The control system may be set up to cause the pneumaticpressure to rise to 20 percent above the last maximum pressure detected.The control system may be set up to cause the pneumatic pressure to riseto above the maximum detected hydraulic pressure detected in a giventime interval, e.g. a 30 second interval preceding shut off of thehydraulic supply. The pneumatic pressure remains constant until thevalve 112 or the main on/off valve 110 is switched on again at B. Thecontrol system may be set up provide a fixed level of positive ornegative bias, rather than bias which is proportional to the hydraulicpressure detected. For example, the air pressure could be a fraction ofa bar greater than the hydraulic pressure at start up, and a fraction ofa bar less than the hydraulic pressure when the hydraulic pressureexceeds the shut-off pressure.

Between B and C, the hydraulic pressure rises which causes the pneumaticpressure to fall until it is 20 percent below the hydraulic pressure.

At C the operator switches off a valve 112 or the main on/off valve 110.The pneumatic pressure again rises to 20 percent greater than the lastdetected hydraulic pressure and remains at that level, thereby ensuringcomplete shut-off, until the operator re-sets the system at D where thepneumatic pressure drops to the minimum start pressure.

Referring now to FIG. 10, there is shown a metering device, thecomprising a body 100 which is moulded from plastics. The body comprisesa stem 101 having a groove 102 therein to permit fitting of the body toa conventional sprayer outlet, or to a sprayer outlet provided with acheck valve according to the present invention. The stem is bored 103,the bore opening into a chamber 111. In the chamber there is mounted anoutlet selector 106 and a metering block 107. The metering block 107comprises an inlet chamber 108 and outlets 109, 110 and another outletwhich is not shown. The outlet selector 106 is provided with one outlet,the diameter of which is not less than the diameter of the largestoutlet of the metering block 107. One end of the metering block isprovided with a grip portion which extends outwardly from the body 100.By gripping the grip portion the sprayer operator can rotate themetering block and align a different aperture with the aperture of theoutlet selector 106, thereby altering the flow of liquid through theoutlet selector 106. The outlet selector 106 is held in place in thechamber 111 by means of a clip 113.

The body 100 further comprises outwardly extending connecting portions104, each portion 104 being provided with chambers 105 with which pipesmay be connected, apertures 112 being provided between the chambers 105and the chamber 111 to permit liquid to flow out of chamber 111 andsubsequently out of the body 100.

FIG. 11a shows the body 100 and the liquid flow path therethrough. Fluidentering chamber 108 passes through the aligned apertures 115 and 116into the chamber 111. It can be seen that a rotational flow of liquidtends to occur. This can lead to the volumes of fluid leaving throughthe apertures 112 being uneven. This is an undesirable effect.

FIG. 11b shows an embodiment similar to that shown in FIG. 11a, and likenumerals are used to identify like parts. In the chamber 111 there isprovided a barrier 114 which extends outwardly from the wall of thechamber 111 towards the outlet selector 106. From the arrows indicatingthe flow of liquid through the chamber 111 it can be seen thatrotational flow does not occur. Because of this, the flow through eachof the apertures 112 is substantially equal. In FIG. 11b, there are twoapertures 112 on either side of the body 100, and the barrier is locatedon the vertical centreline of the body opposite the outlet 116. Theamount of liquid flowing through the apertures on one side of the bodydepends on the position of the outlet 116 with respect to the barrier114. In the embodiment shown in FIG. 11b, the amount of liquid flowingthrough the apertures on one side of the body may be altered by changingthe position of the barrier 114. In FIG. 11b, if the barrier were movedto the left. a greater volume of liquid would pass through the apertures112 on the right hand side of the body, and if the barrier were moved tothe right, a greater volume of liquid would flow through the apertures112 on the right hand side of the body 100.

If the number of outlets 112 on one side of the body 100 differs fromthe number of outlets on the other side of the body, then it may benecessary to move the position of the barrier in order to ensure thatthe same amount of liquid flows through each aperture.

In FIG. 12 there is shown a dribble bar having a selector valve mountedtherein. The tubular members 120 of the bar are pushed on to theoutwardly extending portions 104 of the body 100. Nozzles 119 aremounted in each tubular member 120 and are connected to the body 100 bypipes 118, one end of the pipe being attached to a nozzle, and the otherend being attached to a plug 117 which fits into the chamber 105.

FIG. 13 illustrates a fitting 130 for attachment to a sprayer boomoutlet having a main body 131 having an inlet in the form of a bore 132which enters into the chamber 133. Running centrally through the inletchamber 133 is an internal spigot 134 which is hollow. An elastomericdiaphragm 137 is positioned between one end of the body 131 and theinternal spigot 134 to prevent the flow of liquid through bore 132,inlet chamber 133 and through the chamber 135 of internal spigot 134.Diaphragm 137 is held in position by an end cap 138 which is attached tothe main body 2 by means of a threaded ring member 140. The cap 138 isattachable to an air supply. Cap 138 has an aperture 139 therein whichpermits the passage of air into the chamber 136 between the inner faceof the cap 138 and the outer face of the diaphragm 137. The effect ofsupplying air is to pressurize the chamber 136. Diaphragm 137 moves awayfrom the end of internal spigot 134 when the liquid pressure in chamber135 exceeds the force created by the air pressure in chamber 136 whichacts on diaphragm 137. By adjusting the air pressure in chamber 136 thevalve may be activated at any desired pressure, subject to thespecification of the materials of the diaphragm and the other componentsof the fitting.

When the pressure of the liquid in chamber 135 is equal to or exceedsthe force created by the air pressure in chamber 136 which acts ondiaphragm 137, liquid flows into the hollow centre of internal spigot134. The diaphragm 137 is described in greater detail with reference toFIG. 15.

At one end of the internal spigot 134 there is provided a metering valveassembly which comprises an outlet selector 106 which is locked into themain body 132 by suitable locking means and a rotatably mounted meteringblock 107 having a grip portion extending outwardly of the main body131, the valve assembly being held in place by a dip 141.

The metering block 107 has an internal chamber 108 around thecircumference of which there is located a plurality of apertures 109,110 of different diameters. The outlet selector 106 is also providedwith an aperture (not shown). By grasping the grip portion the meteringblock can be rotated so that the desired aperture is aligned with the ofthe outlet selector. The diameters of the apertures 109, 110 determinethe flow of liquid into outlet chamber 111 which has a portion 141adapted to receive a spray nozzle or dribble bar for instance.

“O” rings are used to seal interfaces between components.

Means may be provided to indicate which of the outlets 109, 110 is inalignment with the aperture of the outlet selector.

Referring now to 14 there is shown a fitting similar to that shown inFIG. 13, except that the check valve is a check valve according to theprior art as opposed to being a check valve according to the invention.

Referring now to FIG. 15, there is shown a sprayer having a tank 167, apump 165, a filter 166 and a pressure regulator 164. The pump 165 drawsfluid from the tank through the filter, and then pumps the fluid intothe feed line 161. The feed line 161 is provided with a check valve 162,which is also connected to return line 160. The check valve 162 may beopened or closed to permit or prevent the flow of fluid through thereturn line 160 back to the tank. The sprayer is provided with an airsupply 150, a filter 151, and a controller 152. The controller 152controls the supply of air via air supply lines 153, 155, 156,157 and158 to the check valves 174 mounted on boom sections 169 to 173, and 162which opens or closes the line 160 which permits return to tank. It canbe seen that the sprayer also comprises a sensing line 154 connected atone end to a sensor 163, which senses the fluid pressure in the feedline 161, and at the other end to the controller 152. The controller isarranged so that there is either a fixed or proportional relationshipbetween the pressure in the air lines and the fluid pressure in thefluid line 161. The check valves 174 are either open or closed.

The controller can supply a high air pressure to any of the boomsections 169 to 173, thereby permitting boom sections to be turned on oroff as the operator desires. When boom sections are turned off, thepressure regulator 164 ensures that the pressure in the feed line 161remains constant by returning more fluid back to the tank 167 throughline 168.

The valve 162 may be adapted to allow constant recirculation of fluidback to the tank 167. This is achieved by controlling the size of theoutlet from valve 162, and thereby controlling the volume of fluidflowing therethrough. The check valve 162 may comprise a metering valveas described herein to provide for different flow rates back to the tank167. Alternatively, a regulating valve such as a rotary valve or a gatevalve may replace the check valve 162.

FIG. 16 illustrates a type of diaphragm which is particularly useful inthe check valve according to the invention. The diaphragm 137 comprisesa seat portion 142 which sits on the end of the internal spigot 134, endportions 144 which provide for attachment of the diaphragm to the mainbody 132. Between the seat portion and the end portions 144 are rollingportions 143. It is these rolling portions which stretch in response tochanges in air or liquid pressure. The rolling portions are arranged sothat they are in tension when the seat portion is seated on the internalspigot. A small positive pressure must be present in the chamber 136 forthe internal spigot to be sealed off. This means that as soon as the airpressure is released, the seat portion 142 will move away from theinternal spigot and fluid will flow from the chamber 133 and through thechamber 135.

What is claimed is:
 1. A rotary metering valve, comprising a bodycontaining a chamber with an outlet thereto, and a metering blocklocated in the chamber and having an inlet connectable to a fluidsupply, at least one outlet, and an outlet selector having at least oneaperture therein for alignment with an outlet of the metering block topermit flow of the fluid therethrough, wherein the outlet selector andthe metering block are relatively rotatable one with respect to theother, means being provided to rotate one of the outlet selector and themetering block, at least one of the metering block and the outletselector having a plurality of outlets such that relative rotationenables different fluid flow rates to be achieved, wherein the chamberhas a plurality of outlets therefrom whereby fluid flowing from themetering block is supplied to all of said outlets, and a barrierextending between a wall of the chamber and the metering block toprevent fluid flowing in a 360° rotary motion around the metering block.2. The rotary metering valve according to claim 1, where in the chamberhas four outlets.
 3. The rotary valve according to claim 1, wherein themetering block is provided with a plurality of outlets and the outletselector is provided with one aperture.
 4. The rotary valve according toclaim 1, wherein the metering block is fixed and the outlet selector isrotatable relative to the metering block.
 5. The rotary valve accordingto claim 1, wherein the outlet selector is fixed and the metering blockis rotatable relative to the outlet selector.
 6. The rotary valveaccording to claim 1, wherein the outlet selector fits over the meteringblock.
 7. The rotary valve according to claim 1, wherein the means torotate the outlet selector comprises one selected from a groupconsisting of a hand grip, a lever, and spanner flats.
 8. The rotaryvalve according to claim 1, further comprising a cap which holds themetering block and the outlet selector in position within the body.